Matter Outflows from AGN: A Unifying Model

We discuss a self-consistent unified model of the matter outflows from AGNs based on a theoretical approach and involving data on AGN evolution and structure. The model includes a unified geometry, two-phase gas dynamics, radiation transfer, and absorption spectrum calculations in the UV and X-ray bands. We briefly discuss several questions about the mass sources of the flows, the covering factors, and the stability of the narrow absorption details.Comment: 6 figures, accepted for publication in Astrophysics and Space Scienc

Magnetic Reconnection in Extreme Astrophysical Environments

Magnetic reconnection is a basic plasma process of dramatic rearrangement of magnetic topology, often leading to a violent release of magnetic energy. It is important in magnetic fusion and in space and solar physics --- areas that have so far provided the context for most of reconnection research. Importantly, these environments consist just of electrons and ions and the dissipated energy always stays with the plasma. In contrast, in this paper I introduce a new direction of research, motivated by several important problems in high-energy astrophysics --- reconnection in high energy density (HED) radiative plasmas, where radiation pressure and radiative cooling become dominant factors in the pressure and energy balance. I identify the key processes distinguishing HED reconnection: special-relativistic effects; radiative effects (radiative cooling, radiation pressure, and Compton resistivity); and, at the most extreme end, QED effects, including pair creation. I then discuss the main astrophysical applications --- situations with magnetar-strength fields (exceeding the quantum critical field of about 4 x 10^13 G): giant SGR flares and magnetically-powered central engines and jets of GRBs. Here, magnetic energy density is so high that its dissipation heats the plasma to MeV temperatures. Electron-positron pairs are then copiously produced, making the reconnection layer highly collisional and dressing it in a thick pair coat that traps radiation. The pressure is dominated by radiation and pairs. Yet, radiation diffusion across the layer may be faster than the global Alfv\'en transit time; then, radiative cooling governs the thermodynamics and reconnection becomes a radiative transfer problem, greatly affected by the ultra-strong magnetic field. This overall picture is very different from our traditional picture of reconnection and thus represents a new frontier in reconnection research.Comment: Accepted to Space Science Reviews (special issue on magnetic reconnection). Article is based on an invited review talk at the Yosemite-2010 Workshop on Magnetic Reconnection (Yosemite NP, CA, USA; February 8-12, 2010). 30 pages, no figure

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In the last years many populations of anurans have declined and extinctions have been recorded. They were related to environmental pollution, changes of land use and emerging diseases. The main objective of this study was to determine copper sensitivity of the anuran of the Amazon Rhinella granulosa and Scinax ruber tadpoles at stage 25 and Scinax ruber eggs exposed for 96 h to copper concentrations ranging from 15 µg Cu L-1 to 94 µg Cu L-1. LC50 at 96 h of Rhinella granulosa Gosner 25, Scinax ruber Gosner 25 and Scinax ruber eggs in black water of the Amazon were 23.48, 36.37 and 50.02 µg Cu L-1, respectively. The Biotic Ligand Model was used to predict the LC50 values for these species and it can be considered a promising tool for these tropical species and water conditions. Copper toxicity depends on water physical-chemical composition and on the larval stage of the tadpoles. The Gosner stage 19-21 (related to the appearance of external gills) is the most vulnerable and the egg stage is the most resistant. In case of contamination by copper, the natural streams must have special attention, since copper is more bioavailable.Nos últimos anos foram registrados muitas extinções e declínios de populações de anuros. Eles estavam relacionados com a poluição do ambiente, a mudanças no uso da terra e ao surgimento de doenças. O principal objetivo deste estudo foi determinar a sensibilidade dos anuros amazônicos ao cobre. Os girinos de Scinax ruber e Rhinella granulosa no estadio 25 e os ovos de Scinax ruber foram expostos por 96 horas a concentrações de cobre entre 15 µg Cu L-1 a 94 µg Cu L-1. A CL50 -96 h dos girinos de Rhinella granulosa, dos girinos de Scinax ruber e dos ovos de Scinax ruber em águas pretas da Amazônia foram 23,48; 36,37 e 50,02 µg Cu L-1, respectivamente. O modelo do ligante biótico foi usado para prever os valores de CL50 para essas duas espécies e pode ser considerado uma ferramenta promissora para essas espécies tropicais e para essas condições de água. A Toxicidade de cobre depende da composição físico-química da água e do estagio larval dos girinos. O estadio 19-21 de Gosner (relacionados ao aparecimento das brânquias externas) são os mais vulnerável e o estagio de ovo é o mais resistente. Em caso de contaminação por cobre, os igarapés naturais devem ter uma atenção especial, uma vez que o cobre é mais biodisponível nesse ambiente

Моделирование биопленок Candida: прошлое и настоящее

Mycoses are often associated with biofilms that are microbial communities encapsulated in a polysaccharide-rich extracellular matrix. Species of yeast-like fungi belonging to the genus Candida are the most common pathogens that cause superficial, deep, and systemic mycoses. Microorganisms that make up the biofilm have recently demonstrated decreased susceptibility to most therapeutic drugs, which contributes to the long-term persistence of infection. At the moment, there is a new branch of preventive and therapeutic medicine, which needs pharmaceuticals to be designed to prevent the formation of biofilms or the destruction of the already formed ones. Recent technological advances have contributed to the elaboration of new approaches to investigating the formation of biofilms and their models and to accumulating extensive knowledge about the influence of different variables on biofilm formation, morphology, and architectonics. There is information on current methods for modeling Candida biofilms and on their advantages or disadvantages in their structure and mechanisms.Микозы часто связаны с биопленками - микробными сообществами, заключенными в богатый полисахаридами внеклеточный матрикс. Виды дрожжеподобных грибов рода Candida - наиболее распространенные возбудители микозов, вызывающие поверхностные, глубокие и системные заболевания. В последнее время микроорганизмы, входящие в состав биопленки, демонстрируют снижение восприимчивости к большинству терапевтических препаратов, что способствует долгой персистенции инфекции. В настоящий момент происходит формирование новой ветви профилактической и терапевтической медицины, нуждающейся в разработке фармацевтических препаратов, предупреждающих образование биопленок или разрушающих уже образовавшиеся. Последние технологические достижения способствовали разработке новых подходов к изучению процесса формирования биопленок и их моделей, а также накоплению обширных знаний о влиянии различных переменных на формирование биопленки, морфологию и архитектонику. Представлена информация о современных способах моделирования кандидозных биопленок, их преимуществах или недостатках в строении и механизмах